LeetCode 1961. 检查字符串是否为数组前缀

示例 1：
输入：s = "iloveleetcode", words = ["i","love","leetcode","apples"]
输出：true
解释：
s 可以由 "i"、"love" 和 "leetcode" 相连得到。

示例 2：
输入：s = "iloveleetcode", words = ["apples","i","love","leetcode"]
输出：false
解释：
数组的前缀相连无法得到 s 。
 
提示：
1 <= words.length <= 100
1 <= words[i].length <= 20
1 <= s.length <= 1000
words[i] 和 s 仅由小写英文字母组成

class Solution {
public:
    bool isPrefixString(string s, vector<string>& words) {
        int n = s.size(), ct = 0;
        string t;
        for(int i = 0; i < words.size(); ++i)
        {
            ct += words[i].size();
            t += words[i];
            if(ct > n) return false;
            else if(ct == n)
                break;
        }
        if(ct < n) return false;
        return s==t;
    }
};